1. Technical Field
The present invention relates to a test apparatus and an information processing system for testing a device under test.
2. Related Art
A test apparatus for testing a semiconductor device or the like includes one or more test units and a control apparatus. Each test unit supplies a test signal to the device under test.
The control apparatus can be realized as a computer connected to the test units via a serial communication cable or the like. The control apparatus issues a command to each of the test units to control the test units. Furthermore, this test apparatus includes, near the control apparatus, a timer apparatus or the like that is frequently accessed by the control apparatus.
One idea considered here is a sequence that involves the timer apparatus beginning to measure time at a timing when a test unit begins a prescribed process, and after a set time has passed, having the test unit begin another process. In this case, the control apparatus issues a command to the test unit to begin the prescribed process, then issues a timer initiation command instructing the timer apparatus to begin measuring time, and finally, after the set time has passed, issues a command to the test unit to begin another process.
When performing this sequence, however, if the propagation time of a command from the control apparatus to the test unit is longer than the propagation time of a command from the control apparatus to the timer apparatus, the timer apparatus begins measuring time before the test unit begins the prescribed process. Accordingly, when performing this sequence, the order of execution of the processes by the test unit and the timer apparatus may not match the order of the commands issued by the control apparatus.
One idea for solving this problem involves issuing a read command to the test unit after the command for the test unit to begin the prescribed process and before the timer initiation command, and then issuing the timer initiation command after receiving from the test unit the data read in response to the read command. As a result, the command issued to the test unit before the timer initiation command ensures that the test unit will already have begun the process. In other words, the order of execution of the processes by the test unit and the timer apparatus can be made the same as the order of the commands issued by the control apparatus.
However, the control apparatus that issues the read command cannot issue another command until receiving from the test unit the data read in response to the read command. Accordingly, when a read command to the test unit is inserted before the timer initiation command, the control apparatus cannot eliminate the pointless wait time.